Air conditioning system



1y15 1941. LB. MILLER-HAL ,249, 84

AIR CONDITIONING SYSTEM Filed Dec. 17, 1934 5U MHER R00" THER MOSTAT HUH'DITY H cOHDENSoR PRE- GOOLI HG AN D PRE- NEATNVG COI L 3 RETUR AIR HUMIDITY COMPRESSOR cONTEOL gwuvm bcyo Leo B. Miller Henry R Dever RIG 3W 3 7% MM,

PatenteddulylS, 1941 AIR CONDITIONING sYsrE Lco B. Miller and Henry F. Dever, Minneapolis,.

Minn,

assignors to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Application December"17,'1934, Serial No. 757,850

26 Claims:

The present invention relates to systems for controlling the condition of air delivered to a' space and is directed particularly to systems of this type wherein the air delivered to the space v is heated or cooled according to demands, together with means to increase or decrease the moisture content of the air, as well as to control the proportions of return airand fresh air that are furnished to the space,

One of the objects of the present invention is the, provision of an -airconditioning "system in which heating or cooling-fluid is selectively connected to coil means which heat or cool the air delivered to the space, the arrangement being such that the flow of heating fluid is directed to the coil means in one manner, whereas the :upply of cooling fluid is directed to the coil means in a different manner.

More specifically, an object of the present invention is the provision of an air conditioning system in which heating fluid is directed to portions of a combined heating and cooling coil means in parallel and cooling fluid is directed to the coil means so that it flows therethrough in a continuous or series path:

A more specific-object of the invention is the refrigeration system is utilized for the purpose of removing-moisture from the air to be conditioned as by cooling a dehumidifying coil while the coolingwater' is first passed through a cooling coil andthen through the condenser.

Another object of the invention is the provision 'of independent means to cool the water .cooled device or condenser.

Other objects of.the invention include the combination of the systems set forth above. I g A further object of the invention is the provision of means, preferably automatic, to place the various systems heretofore set out on a cooling cycle or a heating cycle according to demands or necessity.

Still further objects of the invention include the controlling of the volumes of return or with- 'drawn' air furnishedto the space in combination with the cooling systems and combined heating and cooling systems disclosed above.

Other objects comprise the controlling of the fan or blower which delivers the air to the space and providing means for increasing the moisture content of such air when necessary.

provision of an air conditioning system wherein a first coil is located in thepath of return or withdrawn air, and a second coil is located in the path of the fresh air only, cooling fluid being passes through the first coil and then passes through the second coil, whereas heating fluid is directed to said coils in parallel. In the preferred form of the invention, means responsive -to the conditions of the space to be controlled control the flow of cooling fluid .to both said coils and also control the flow of heating fluid to one of said coils, while means responsive to outdoor conditions control the flow of heating fluid to the other of said coils.

Another object of the invention is the provision of an air conditioning system in which chilled or refrigerated water is supplied by means including a water cooled device, this chilled water being supplied to one air conditioning coil, whereas cooling water is supplied to anot-herconditioning coil and isthen utilized to cool said water cooled device.

More specifically, it is an object of the present invention to pass cooling water through an air conditioning device after which the cooling water is utilized to cool thecondenser of a mechanical refrigeration system which also functions to condition'the air to be controlled. Specifically, the

directed to the coils in series so that it first Further objects include a complete combination of all of these functions or operations, as

well as various sub-combinations thereof, and

.will be found in the detailed description, the

drawing, and the appended claims.

For a more complete understanding of the inventlon reference may be had to the following detailed description and accompanying drawing which is a schematic showing of the complete system of the present invention.

Referring first to the drawing, the system of the present invention is shown applied to an air conditioning unit which is herein illustrated as comprising an air conditioning chamber Ill from which the conditioned air is discharged into the room or space to be "conditioned. Communicating with the inlet of the air conditioning chamber In is a return air duct H and a fresh air duct I2 which respectively convey return and fresh air to the air conditioning chamber Hi under the control of any suitable mixing damper arrangement. The mixing damper arrangement is herein illustrated as comprising a return air damper 13 which is mounted in the return air duct l I and is pivoted upon a shaft l4; and a fresh air damper I 5 which is located in the fresh air duct l2 and is pivoted 'upon a shaft I 6. Circulation of air to the space to be conditioned and through the air conditioning chamber In may be accomplished in any of the usual manners, such as by a fan ll which is located in the air conditioning chamline wire 31.

through suitable connections such as those illusditioningchamber |8,-a combined pre-cooling andpre-heating coil 28 is located in the fresh air duct |2 for pre-cooling or pro-heating the air passing therethrough, and a cooling and heating coil 2|, which is in the nature of a main heating and cooling coil or re-cooling and-reheating coil, is located in the air conditioning trated by the belt l9. For the purposes of heating and cooling the air passing to the'air conchamber l0 so that both the fresh air and repurpose of adding water to or humidifying the air passing therethrough, and a dehumidifying coil 23 also located in the air conditioning chamher It! for the purpose of chilling the air passingtherethrough suificientlyto remove moisture therefrom.

The dehumidifying coill 23 is supplied with chilled water from awater cooler 24.' .A pump her It andisxdriven by an electric motor l8. summer. :water ,flows from a supply pipe- 45 to a three-way valve 46. The water may then pass by way of pipes 41 and 48 through an onand-oif electrically operated valve 49' directly to thecondenser 40 and out a'discharge pipe 58.

Thiswater may also fiow from the three-way I pipe 50.

25 that is operated by an'electric :motor 26 circulates'the chilled water from thewaterv cooler changes in relative humidity and isherein shown as'comprising arhair-element. One end of the element 28- is fixed as indicated at 29, and its other end i's'secured to a switch carrier 30 that is pivoted as at 3|. A spring 32 has 'one of its-ends securedto the springscarrier 38,.and its otherend is secured as indicated at 33, the-spring'32' During the winteroperation the coils 20 and a suitable source of heating'fluid which is hereinv shown as'supplied by' a hot water boiler 69. I

. The hot water passes fromthe boiler 68 through a pipe 6|, an electrically operated valve 62, and a pipe 63 where the circuit splits, one part going by way of a pipe -'64 andelectrically operated valve'65, pipe 52, coil 2|, 'and pipe 53 to a pipe 65, whereas-theother portion of'the circuit goes I by. way of pipe-56, valve 55, pipe 54, and coil 20 to pipe 65. These combinedxreturns thenfiow' through an electrically operated valve 66 and-a pipe 61 to the boiler 60.v a

" The valves 58, 62,-and 66am directly-controlled by a change-over relay generally indicated at 68.

This relay includes a relay-coilf69 that operates an armature' lll, 'Armature18 controls switch arms 1|, 12, 14,] and 15.; Upon energization of g y relay coil "69, switch arm 1-| engages a contact 16,

operating to place the humidity responsive element 28. under tension at all 'times. rThe switch carrier 38 carries a mercury switch-34, and the" arrangement is such that if the relativehumidity reaches some excessive value of say 60%; the consequent expansion of the element'28 will-be suflicient to allow spring 32 to move switch. carrier 30 about its pivot 3| until the mercuryswitch 34 closes. Whenever the relative humidity drops to some value'slightly below 60%, the-contraction of the element 28 returns the mercury switch 34 to open position, asshown in 1 of the drawing. Themercury switch 34 controls-themotor 26 by a "circuit which includesa linewire" switch arm '12 engages a. contact 11, switch arm 14 engages a contact 18, and switch arm 15 en '1 I gages a contact 19. When relay coil 69 is de-' energized, switch arm 1| engages a contactflfl,

switch arm 12 engages a contact 8|, switch arm 14 engages a contact 83, and switcharm 15 dis.- engages its contact'19. I The switch arm 12 and the contacts 11 and 8| constitute the switching mechanism that directly controls the valves 58,

62, and 6'6. The arrangement is such that with wire; 86, valve 62, wire 81, and return line wireBB.

'- Similarly, the closing circuit for valve 66 is 'as'" follows:- line wire-84, switch arm 12, contact 11,

- wire 85,. wire 89, wire 90,valve 66,.wire 9|, wire 92; andreturnline wire 88. The opening circuit 35, mercury switch 34, wire 36, motor 26, and-a;-

The water cooler 24 is'cooled by-a refrigeration system that includes a compressor 38 which is '-driven by an electric motor.39,'a co'ndenser 49,

and an expansion valve 4| that controls the flow of refrigerant to "an expansion coil contained within the water cooler 24. The compressor 38 operates in the usual manner to compress the refrigerant after which it passes to the condenser '40 by means of a pipex42. The compressed refrigerant is then cooled, as will be herein after explained-Salter which it passes to the expansion to the compressor'38 through a pipe '44.

City water, well water, or the like, is utilized to cool the condenser 40 as well as to cool the cooling coil 2| and the pre-cooling coil 20 during the for valve-58 is asfollowsz'linewire 84, switch arm v 12, contact 11 wire, 85,1'wir'e 89, wire-93; valve 58, wire-94, wire92, and returnwire88. When I switch arm 12 engages 'contact8l' the valves-62 and are opened andthe-lva'lve 58' is closed- I The opening circuitfor'valve 62- is asfollowsz line- *wire 84, switch arm 11 contact B|, wire 95, wire 96'; valve 62, and wire 81 tQ'IGtUIH line 88. Similarly; the-opening circuit forvalve 66 is as follows: line wire 84, switch arm 12,.contact 8|,-

lay '68 is energized,. the valves 62 and 66 are f closed to prevent circulation of water to or from the boiler..60 and the, valve 58 is opened to 'allow'circulation; of water-to thelcondenser 40 after it has passed through the coils 2| and 2|!- in series. On the otherhand, when coil 69 of and 66 are opened to I permit circulation of boiler water from the boiler 60 to thecoils 20 and 2I in parallel, and the valve 58 is closed to prevent any of this boiler water from flowing to the condenser '40 by way of pipe 59.

The valve 55 is controlled by the change-over relay 68 indirectly through the medium of a switch I that is operated by valve 66 and is also controlled by an outdoor thermostat generally indicated at IOI; The switch I 00 is in the position shown when the valve 66 is closed. The outdoor thermostat IN is shown as of the volatile fluid type. and comprises a controlling bulb I02 that is connected to an expansible member I03, herein shown as a bellows, by a connecting tube I04. The bellows. I03 operates a pivoted switch carrier I05 that in turn supports a mercury switch I06. The capsule I02, bellows I03,

and connecting tube I04 are charged with the proper amount of suitable volatile fluid, as is well known in the art, so that whenever the temperature to which the bulb I02 responds is above 40 the mercury switch I 06-is in the position shown wherein its left-hand electrodes are closed. If the temperature to which thebulb I02 responds falls appreciably below 40 F., then the volatile fluid pressure is reduced allowing bellows I03 to contract sufliciently to move mercury switch I02 to the opposite position wherein its right-hand, electrodes are closed. As 'previously stated, thethermostat IN is an outdoor engagement with a. cold contact lllwhen the room temperature is at or below 70 F. When the switch arm H6 engages cold contact II 8, the

valve 65 is opened by the following-circuit: line j wire II9, bimetallic element II5, contact blade H6, contact H0, wire I20; valve 65, and return line wire I2I. When the contact blade II6 en-- gages hot contact II1, thevalve 65 is closed by a circuit as follows: line wire I I9, bimetallic element II5, contact blade II6,' hot contact II1, wire I22, valve 65,v and return line wire I2I. There- 'fore, when valves 62 and 66 are-openfor winter operation, the flow of heating fluid to the coil 2| is controlled by the winter room thermostat through the valve 65.

The three-way valve 46 includes a valve disc I25 which prevents communication with'pipe 5| when in its lowermost position and prevents communication with pipe "when in its upper position. The valve diskI25 is carried by a valve stem I26 which is controlled by an electrical operator I21. This operator I21 is controlled by the combined action of a summer room thermostat and the switch, arm and contacts 18 and 83 of the change-over relay 68. The summer room thermostat includesa bimetallic actuating element I28 that controlsta contact blade I29.

lWhen the room temperature rises to some value such as 80 F., the contact blade I29 engages a hot contactl30, and when the room temperature falls to some lower value of say 318 E, the contact thermostat, and its controlling bulb I02 may be conveniently located in the-freshair duct I2 as shown With the mercury switch I00 in the position shown, the valve 55 is opened irrespective of the condition of mercury switch I06 by a circuit as follows: a line wire I01, left-hand electrodes of mercury switch I 00, wire I08, wire I09, valve 55, and return line wire H0. The valve 55 is therefore always open when the valve 66 is 'closed by the change-over relay'68. When the,

valve 66 is opened by the change-over relay- 68,

the mercury switch I00 moves to a position .opposite to that shown, wherein its left-hand electrodes are open and its right-hand electrodes are closed. Under these conditions, the valve is placed under the control of the mercury switch I06 of outdoor thermostat IOI. Assuming mer-.

cury switch I00 to be in such opposite position and the mercury switch I06 in the position shown,

then the valve 55 closes by the following closing circuitz' line wire I01, right-hand electrcdes ofblade I29 engages a cold contact I3 I. switch arm 14 is engaging contact 63, the operator I 21 maintains the valve disc I25 in .its lower position irrespective of the condition of the summer room thermostat. This circuit is as follows: line wire I32, switch arm 14,contact 83, wire I33, wire I34, operator I21, and return line wire I35. When the'switch arm 14 is engaging contact 18, however, the operator I21 is under the control of the summer room thermostat. If the contact blade I29 engages its hot contact I30,

' the operator I21. is energized to raise the valve I position by the following circuit: line wire I32,

mercury switch I00, wire III, left-hand electhe coil 20, the flow of heating fluid to the coil 20 is controlled by outdoor temperature through the valve 55 to permit the flow of heating fluid to the coil 20 only it the outdoor temperature falls below 40 F. The valve is controlled directly by a winter room thermostat that includes a bimetallic actuatingelement II 5 that operates a switch arm I I6 to move the same into engagement with a disc I25 bythe following circuit: line wire I32, switch arm 14, contact 18, wire I36, bimetallic element I28, contact blade I29, contact I30, wire- .I31, operator I21, and return line wire I35. 0n the other hand, when the contact blade I29. en-

gages the coldcontact'l3l, the operator I21 is energized to move the valve disc I25 to its lower switch arm 14, contact .18, wire I36, bimetallic element I20, contact blade I29, cold contact I3I, wire 138, wire I34, operator- I21, and return line wire I35. In this manner, during winter operation when therelay coil '69 is deenergized the valve disc I25 is maintained in its lowermost turn line wire II0. In this manner, with valves I 62 and 66 open so as to connect the boiler 60 to position irrespective of the room temperature so that city water, well water, or the like, cannot" flow to pipe 5|. During summer operation, however, when relay coi1'69 is, energized the valve disc I25 is lifted to permit the flow of such 0001- mg water to'the pipe 5I and therefore to the coils 2I and 20, in series, whenever the room temperature becomes too high.

The boiler 60 has-been illustrated herein as Y supplying the-heating fluid to the coils 20'and 2| for winter operation, but, it is tobe understood that any suitable source of heating fluid could be utilized. The boiler 60 is controlled by a mercury switch I40 that is carried by an arm I which is operated by the'operator 121- of the three-way hot contact II 1 when the room temperature is at or above 72 Hand to move the same into valve 46. The boiler 60 is additionally controlled by a boiler control generally indicated at, I42.

When the through a connecting tube I45.

The boiler is herein shown as fired by an oil burner which includes a burner motor I43. The boilcrcontrol I42 operates to energize the burner motor I43 whenever the boiler water temperature falls to some minimum value thereby to maintain a predetermined minimum boiler water ,temperature, providedthe three-way valve 46 is in the position shown. This boiler control I42 includes a controlling bulb 13 that is connected to an expans ble member -I44, herein shown as a bellows, This bellows operates a pivoted switch carrier I46f that supports a mercuryswitch I41. Whenever the boiler temperature falls to some predetermined mini- -mum value such as 140 F., the mercury switch I41 closes, and when the boiler temperature rises to some slightly higher value the mercury switch I41 cpens. The circuit for the burner motor I43 is as follows: linewire. I48, mercury switch I40, wire I50, mercury switch I41, wire II, burner motor I43, and return line wire I52. As a result, the burner motor circuit cannot be completed if the mercury switch I is in the position opposite to that shown by reason of valve disc I25 being in its upper position. In this manner, during summer operation the boiler control I42 can control the burnermotor I43 whenever the summer During summer operation the flow of-cooling water to the condenser by way of pipe 41 and the operation of the compressor motor 39 are controlled by a thermostat responsive to the temperature of'the water in water cooler 24. This thermostat includes a controlling bulb I that is connected to an expansible element I56, shown as a bellows, by a connecting tube I51. The bellows I56 controls a pivoted switch carrier I58 that in turn supports a mercury switch I59. The merswitch arm 1|, contact .10, wire'l64, right-hand electrodes of mercury switch I59, wire I66, valve 49, and return line wire I63. The valve 49 controls the mercury switch I10 to maintain the same in open'position as long as valve 49 is- I10, wire I12, compressor motor 39,-and return line wire I13.' In this manner the .compressor cury switch I59 is in the position shown wherein the left-hand electrodes are closed when the temperature of the water in water cooler 24 is sufliciently low; But if the temperature of the water in the water cooler rises to some predetermined high value, 42 F., for example, the

mercury switch I59 moves to the position opposite that shown wherein theright-hand electrodes thereof are closed. When the relay coil 69 is deenergized so that switch arm 1I engages contact 80, the valve 49 is closed irrespective of the condition of mercury switch I59 by a circuit as follows: line wire I60, switch arm 1I, contact 80, wire I6I, wire I62,'valve 49, and return line wire I63. When the apparatus is on summer operation by reason of energization of relay coil 69 so that switch arm 1I engages contact 16, then the valve 49 is directly controlled by the mercury switch I 59. With the mercury switch I59 in the position shown in Fig. 1, the valve 49 remains closed by a circuit as follows: line wire I60, switch arm 1I, contact 16, wire I64, lefthand electrodes of mercury switch I59, wire I65, wire I62, valve 49, and return line wire I63. But when the temperature of the water in water cooler 24 rises to 42 F. so as to move mercury switch I59 to the opposite position, the valve 49 is opened by the following circuit; line wire I60,

motor 39 cannot be energized and the condenser water-valve 49 cannot be opened when the apparatus'is'on winter operation. When the appa- 49 are placed under the control of the chilled water thermostat. Y

l The change-over relay 68 maybe controlled manually or automatically in any manner prop erly to change the system from summer to winter operation, and vice versa, and is herein shown as controlled byan outdoor temperature change-over thermostat generally indicated at I15. This thermostat is also shown as being of the volatile fluid type and includes a control bulb I 16 that is connected to an expansible member I11, in the form of a bellows, by a connecting tube I18. The bellows I11 operates a pivoted switch carrier I19 that supports a mercury switch I80. This change-over thermostat I15 is preferably of .the type that operates on an appreciable temperature difierential. Such differential thermostats are well known'in the art, and in the I present instance the mercury switch I is moved a to closed position when the outdoor temperature rises to 75 F. and remains'in closed position until the outdoor temperature -falls to 70 F.

This mercury switch I80 controls the margintion of relay coil 69 by a circuit that includes a line wire I8I, mercury switch I80, wire I82, relay coil 69, and return wire I83. In thismanner, the change-over relay coil 69 is energized whenever the outdoor temperature rises to 75 F. andthen remains energized until the outdoor temperature subsequently falls to 70 F.

The fan motor I8 is controlled conjointly by the change-over relay 68 and by a ductthermostart that includes a bimetallic actuating element I that positions acontact bla'de I86 to move the same from engagement with a hot contact I81 if the temperature of the air issuing from the air conditioning chamber I0 falls to some minimum value such as 65 F. During the sum-.

mer operation when switch arm 15 is engaging contact 19, the fan motor I8 iscontinuously energized by a circuit as follows: line wire I88, wire I89, contact 19, switch arm 15, wire I90, fan motor I 8, and return line wire 'I9I. But during the winter operation when switch arm 15 is separated from contact 19, then the fan motorv I8 is placed under the control of the duct thermostat by a circuit as follows: line wire I88,-

wire-I92,'bimetallic element I65, contact blade In this manner trol of a valve 200. This valve is controlled by a moisture responsive control generally indicated at 2!" which includes a humidity responsive element 202 having one of its ends secured, and herein disclosed as.a hair element. Its other end is connected to a switch carrier. 203 that supports a mercury switch 200. A coiled spring 205 serves to maintain the humidity responsive element 202 under proper tension. Whenever the relative humidity of the room or space to be controlled is above some minimum value such as 40%, the parts are in the position shown wherein mercury switch 204 is in open position. But if the relative humidity falls below this value of 40%, then the humidity responsive element 202 contracts sufficiently to move mercury switch 204 to closed position. The mercury switch 204 controls energization of the valve 200 by a circuit as follows: line wire 206, mercury switch 204, wire 201, valve 200, and return line wire 208. In this manner. water is supplied to the spray 22 whenever the relative humidity of the room or space falls below the desired value of 40%.

The mixing dampers I3 and I5 are operated by a proportioning motor mechanism generally indicated at 2| 0. This proportioning motor may be of the type shown and described in the Taylor Patent 2,028,110, dated January 14, 1936. This motor includes a crank 2 that is moved through a maximum of 180 angular degrees. The crank 2| I is connected to the fresh air damper I5 by a link 2 I2, and the fresh air damper I5 is, in turn, connected to the return air damper I3 by a link 213. As shown, crank 2 is in mid-position which causes the fresh air damper I5 to be wide open and the return air damper I3 to be closed. If crank 2II rotates in a clockwise direction, the damper I5 will be rotated counter-clockwise to ward closed position and this will cause counterclockwise rotation of damper I3 towards open position. Conversely, if the crank 2| I rotates in a counter-clockwise direction from the position shown, the damper I5 will be rotated clockwise towards closed position and damper I3 will besimultaneously rotated counter-clockwise towards open position. Therefore, if the crank 2II rotates in either direction from mid-position, the fresh air damper will be moved towards closed position and the return air damper moved towards open position.

Upon reference to the Taylor patent, it will be found that the proportioning motor 2I0 is provided with a three-wire control circuit and is adapted to assume intermediate positions in ac-- cordance with the relative amounts of resistance connected across each side of the control circuit. The proportioning motor 2I0 is provided with three control terminals marked R, W, and B. When equal values of resistance are connected across terminals R and W and terminals R and B, the motor will assume mid-position as shown for causing the fresh air damper I5 to be wide open and the return air damper I3 to be closed. However, if the resistance between terminals R and W is decreased without corresponding decrease in resistance between terminals R and B,

the crank 2 will rotate clockwise an amount proportionate to the change in resistance. Conversely, if the resistance between-terminals R and B is decreased without corresponding decrease in resistance between terminals Rand W, crank 2 will rotate in a counter-clockwise direction an amount proportionate to the change in resistance.

The motor 2I0 is adapted to be controlled by means of a potentiometer type outside temperature responsive thermostat 2I5, a return air thermostat 2I8, and rheostats 2I6 and 2". Referring to the thermostat 2I5, this thermoe stat is diagrammatically illustrated asconsisting of a resistance 230 which cooperates with a slider 232 for forming a potentiometer controller for the motor 2I0. This slider 232 may be actuated in accordance with the fresh air temperature by any suitable type of thermostatic element such as a coiled bimetallic element 230 located in duct 12. This instrument may be so designed and adjusted as to cause the slider 232 to engage the right-hand end of resistance 230 when outside temperature rises to F., while engaging the left-hand end of resistance 230' when outside temperature falls to 40 F. It should be noted that the resistance 230 is tapered in a manner to cause the electrical center of this resistance -to be located at the point cont-acted by slider 232 when the outside air temperature is at 70 F.

Referring to the return thermostat 2I8, this thermostat may include a control bulb 224 located in the return air duct II, this bulb being connected to a bellows 225 by means of a capillary tube 220. The bellows 225 actuates a mercury switch carrier 221 which is pivoted at 228 and which carries a mercury switch 229. Upon an increase in return air temperature, the vapor pressure of thevolatile substance'contained in bulb 224 will increase thus causing the bellows 225 to expand for tilting mercury switch 229 towards closed position. Upon a decrease in return air temperature, the bellows 225 will contract for allowing mercury switch 229 to be tilted towards open position. This instrument may be so designed and adjusted as-to cause the mercury switch 229 to be closed when the return air temperature is at or above F., while remaining the various controllers, it will be noted that terminal R of motor 2I0 is connected by wire 203 to the slider 232, and that terminal 3 is connected by a wire 2" and rheostat 2| 6 to the lefthand end of resistance 230. The right-hand end of resistance 230 is connected by wire 216, rheostat 2" and wire 214 to terminal W of the motor 2I0. The slider 232 therefore determines the portions of resistance230 which are connected across terminals R and W and terminals R and B of motor 2I0. With the parts in the position shown, the return air temperature is below 85 E, which causes mercury switch 229 to be open. Also, the fresh air temperature is at 70 as indicated by the slider 232 engaging the electrical center of resistance 230. This engagement of slider 232 with the electrical center of resistance 230 causes he slider 232 to divide the resistance 230 equally into one portion which is connected across terminals R and B and another portion which is connected across terminals R and W. Due to the rheostats 2"; and 2I1 being set for equal values of resistance, the same amount of when the outside 6 resistance is connected across terminals R and W as there is connected across terminals R and B. This has caused the crank 2 of motor 2"! to assume mid-position in which the fresh air damper I is open and the return air damper I3 is closed.

If the outside temperature decreases below 70 F., the slider 232 will move to the left across resistance 230 thus decreasing the portion of resistance 230 which is connected between terminals R and B andincreasing the portion of this resistance which is connected across terminals R and W. This will cause crank 2 to rotate in a counter-clockwise direction for thus closing damper I5 and opening damper I3 in proportion to the movement of slider 232 on resistance 234. Therefore, as the outside temperature falls below 70 F., the fresh air damper I5 will be moved towards closed position and the return air damper I3 will be moved toward open position. When outside temperature fails to 40 F., the slider 232 will engage the left-hand end of resistance 230, thus removing the entire resistance 230 from the circuit between terminals R and B, and placing the entire resistance 230 across terminals R and W. In the absence of rheostat 2I6, terminals Rand B would be shortcircuited which would cause the motor 2I0 to assume its extreme counter-clockwise position for completely closing fresh air damper I5 and completely opening return air damper I3. How- 'ever, due to the resistance of rheostat 22I, this substantial short circuit is prevented which causes the motor 2 to stop at a position short of closed position for damper I5. This provides for maintaining at least a minimum open position for damper I5 for thus providing a predetermined minimum amount of air for ventilation purposes at all times. By adjusting the rheostat 22 I the minimum position for damper 13 may be varied as desired.

If outside temperature increases above 70 F., the slider 232 will move to the right across resistance 230, thus decreasing the portion of this resistance which is connected across terminals R and W and increasing the portion of this resistance which is connected across terminals R and B. This will cause the crank 2 to rotate in a clockwise direction for thus moving damper I5 towards closed position and moving damper I3 towards open position. When outside temperature rises to 80 the right-hand'end of resistance 230, thus placing the entire resistance 230 across terminals R and B and substantially short-circuating terminals Rand W except for the action of the rheostat 2I'I. This rheostat 2" determines the minimum open position of the fresh air damper I5 when the system is operating on the cooling cycle. Thus if this rheostat is set for zero resistance, the damper will be closed completely, and as this thermostat is adjusted for increasing the portion of resistance 222 in circuit with terminals R and W, the minimum supply of fresh air will be increased. It will thus be seen that temperature is above 80 F., the damper I5 will remain slightly open an amount determined by the adjustment of rheostat 2II for providing the necessary air for ventilation purposes. g

In the event that outside temperature rises to a value which imposes a load upon-the cooling system which cannot be carried simultaneously'with the load imposed by cooling the air for ventilation purposes, the space temperature F., the slider 232 will engage dew point temperature the supply of outdoor or either opposite position can will rise above the setting of thermostat 2I8, thus causing closure of mercury switch229. This mercury switch 229, it will be noted, is connected by wires 292 and 293 in a manner to short-circuit the rheostat 2 I 1. Thus when mercury switch 229 closes due to excessive space temperature, the rheostat 2 I I will be short-cirouited for thus causing the damper I5 to close completely. This will reduce the load upon the conditioner for enabling it to maintain a satisfactory temperature within the conditioning space.

From the foregoing it will be seen that a full supply of fresh air is taken into some intermediate value, such as 70 F., and that fresh air is reduced if the outdoor temperature either rises above or falls below this value. However, a larger fall in outdoor temperature is required in this particular embodiment of the invention to close off the supply of fresh air completely or to reduce the supply of fresh air to the manually set minimum than rise in outdoor temperature is required to bring about the same results. Further, if the room or space temperature becomes excessive because of the taking in of this minimum supply of fresh air of high temperature, then the fresh air damper is automatically moved to full closed position. It will be obvious that by changing the manner in which the resistance 230 is wound, the amount of temperature change required to move the damper from the position shown to be varied as desired.

Operation of the complete system With the parts in the positions shown, the outdoor temperature has recently been at or above 75 F. since the mercury switch I of the change-over thermostat I15 is closed, but the outdoor temperature has lowered to substantially 70 F. as indicated by the position of the outdoor temperature responsive resistance thermostat 2I5. Since the outdoor temperature is substantially 70 F., the return air damper I3 is in closed position and the fresh air damper I5 is in full open position. The relay coil 69 of the changeover relay 68 is energized since mercury switch I80 is closed. As a result, the values 62 and 66 are closed and the valve 58 is opened by the circuits heretofore set out. Also, the valve 55 is open and cannot be controlled by the outdoor thermostat IOI. Similarly, the three-way valve 46 is under the control of the summer thermostat. The boiler control I42 can therefore. operate the burner motor I43 whenever the summer room thermostat is not calling for heat, but the boiler water is prevented from flowing to the coils 20 and 2| by reason of the closure of valves 62 and 66. The room temperature is between the desired values of 78 F. and 80 F., and the chilled water temperature is below 42 F. Also, the relative humidity of the room or space is between 40% and 60%.

In the summer the relative humidity will be excessive rather than insuflicient, so that the humidity control 20I will water to the spray 22. However, the relati e humidity may often become excessive resulting in operation of humidity control 21 energizing the pump motor 26; Whenever-this happens chilled water will be caused to flow through the dehumidifying coil 23 whereby to lower the temperature of the air passing 'thereover below its and cause a condensation In this manner, the relanever operate to supply of moisture therefrom.

the conditioning I chamber I0 when the outdoor temperature is at tive humidity may be lowered under the control of the humidity control 21. Whenever the chilled water has absorbed sufficient heat from the dehumidifying coil to raise the temperature of the same above 42 F. the controlling bulb I55 will cause movement of mercury switch I59to its opposite position whereby valve 49 will be opened and compressor motor 39 will be energized. The refrigeration system thereupon operates to cool the water in therwater cooler 24, and cooling water for the condenser is supplied by supply pipe 45 through the three-way valve 46, pipe 41, valve 49, and pipe 48 to the condenser. Whenever the temperature of the water in the water cooler 24 has been lowered sufliciently, the mercury switch I59 returns to the position shown in Fig. 1 thereby closing valve 49 and deenergizing the compressor motor 39. The fan ll, of course,

is in constant operation during the summer cycle as heretofore explained. I

If the room temperature should rise above 80 F., then the operator I21 will be energized to lift the valve disc I25. The water supply pipe 45 is thereupon connected to the coils 2 I and 20 in series and in the order named. Water flows from supply pipe 45 through three-way valve 46, pipe 5|, pipe 52, coil 2|, pipe 53, coil 20, pipe 54, pipe 56, pipe 51, and pipe 59 to the condenser 40. In this manner, whenever the room temperature becomes excessive during the summer operation cooling water is directed through the coils 2I and 20, in series, to obtain a counter-flow action whereby the coolest water is utilized for the final -65 valve 56, and pipe 51 back to the'boiler. burner motor I43, of. course, is now continuously I nected to the coils and 2| .in parallel. If the room temperature'fallsto 68 F., the valve "65 will be opened and boiler water will flow from the boiler 60 through pipe 6I,'va1ve 62, pipe 63, pipe 64, valve 65, pipe 52, coil 21, pipe, 53, pipe The controlled by the boiler control I42 to maintain a minimum boiler water temperature. In this manner the winter. room thermostat permits circulation of .boiler water to the coil 2I whenever the room temperature becomes too low while the system is operating on the winter cycle. If the outdoor temperature should fall below 40 F., then theoutdoor thermostat IOI opens valve 55 whereby boiler Water flows toprecooling action, and this water is then used fora pre-cooling operation. Further, this water is.

then directed to the condenser to cool the same irrespective of whether or not the compressor 38 is in operation. In this manner, the cooling water is used for as many purposes as possible before being discharged. During such period, the boiler control is unable to operate the burner motorsince mercury switch I40 is open.

Rise in outdoor temperature will be accompanied by. a gradual closing of the fresh air damper I5 and a gradual opening of the return air damper I3 until some maximum' outdoor temperature is reached, such as 80 F., after which the fresh air damper I5 will remain in some minimum position depending upon the set'- ting of rheostat 2II. But if the room temperature rises too high because of the inability of the cooling apparatus to maintain it within the limitation of the summer room thermostat, then the thermostat 2I8 will shunt the rheostat 2" as heretofore described and cause a,complete:

the water cooler thermostat.

In addition, the valves 62 and will be opened, and the valve 53 will be closed. Further,-the valve 55 willbe placed under the control of the outdoor thermostat MI, and the three-way valve 46 will be maintained in the position shown. The boiler 60 is therefore contem is in operation.

heating coil 2'0 as follows: from the boiler through pipe 6|, valve 62, pipe 63, pipe 56, valve 55, pipe 54, coil 20, pipe 65, valve 66 and pipe Iil to the boiler 60.

In the wintertime the relative humidity never becomes excessive so that pump motor 26 is never energized. On the other hand, the relative humidity. often becomes too low during the winter, and in such an instance the humidity control 2M energizes valve 200 to allow the supplying of water to the spray 22 whereby to add moisture to or humidity the air passing through the conditioning chamber- I0.

The system of the present invention, therefore, provides an arrangement in which cooling or heating is selectively applied to the air which is discharged into the room or space. This heating.is accomplished in the winter by two coils which are in parallel, one being controlledby the room orspace temperature, and the other .being controlled by the outdoor temperature.

In the summer the cooling is obtained by placing these coils in series so as to obtain a counter-flow action, and the cooling water is additionally utilized to cool the condenser of a refrigeration system, which, in the present instance, is utilized to supply cold water for dehumidiiying purposes. This refrigeration system is under the control of a relative humidity control which also operates tosupply cooling water to the condenser whenever the refrigeration syssummer to winter operation, and vice versa, may be obtained in any desired manner but is herein obtained automaticallyby relatively wide fluctuations in outdoor temperature. In addition, the

mixing dampers I3. and I5-are controlled to supply a minimum quantity of outdoor air at low outdoor temperatures, to increase this quantity of outdoor air gradually as theoutdoor tempera-- ture rises to an intermediate or comfont value,

and gradually to reduce the quantity of outdoor air to ,a minimumas the outdoor temperature continues to rise and becomes .excessive. Further, manual means are provided to adjust these minimum quantities of outdoor .air under extreme cold and extreme hot conditions, and autom-atic means are provided to prevent the taking in-of this minimum quantity of outdoor air during the summer operation if the room or space temperature becomes excessive .by reason thereof. I

It will ,be apparent that many changes and modifications may be made in the specific system herein disclosed without departing from the f spirit of the invention, and we therefore intend This change-over from We claim; I

1. An air conditioning system of the class described, comprising, in combination, means to pass air to a space, first and second coils over which said air passes in the order named, a source of heating fluid, a source of cooling fluid, piping connections interconnecting said coils and sources of heating and cooling fluids, valve means in control of said connections, and control means controlling said valve means selectively to direct the'hea-ting fluid through said coils in parallel or to direct the cooling fluid through said coils in series.

2. An air conditioning system of-the class described, comprising, in combination, means to pass an to a space, first and second coils over which said air passes in the order named, a source or heating fluid, a source of cooling fluid, piping connections interconnecting said coils and sources of heating and cooling fluids, valve means inlcontrol of said connections, and control mean controlling said valve means selectively to direct the heating fluid through said coils in parallel or to direct the cooling fluid rect the heating fluid through said .coils in parallel or to direct the cooling fluid through said coils in series, and means responsive tothe temperature of the space additionally controlling said valve means to permit such flow of cooling fluid to said coils when the space temperature becomes too high and to permit flow of heating fluid to at least one of said'coils when the space temperature becomes too low.

4. An air conditioning system of the class described, comprising, in combination, means to Pass airto a space, first and second coils over which said air passes in the order named, a

source of heating fluid, a source of cooling fluid, piping connections interconnecting said coils and sources of heating and cooling fluids, valve means in control of said connections, control means controlling said valve means selectively to direct the heating fluid through said coils in parallel or to direct the cooling fluid through said coils in series, means responsive to the temperature of the space additionally controlling said valve means to permit such flow of cooling fluid to said coils when the space temperature becomes too high and to permit flow of heating fluid to one of said coils when the space temperature be-' comes too low, and a thermostat responsive to outdoor temperatures to additionally control said valve means to permit the flow of heating fluid to the other of said coils when the'outdoor temperature falls to a predetermined value.

5. An air conditioning system of the class described, comprising, in combination, means to pass a mixture of withdrawn air and fresh air to a space, a first coil located in the path of said air mixture, a second coil located in the path of the fresh air only, a source of heating fluid, a source of cooling fluid, pipes connecting said sources of fluid and coils, valve means in control of said connections, and means in control of said valve means selectively to connect the source of heating fluid to both said coils in parallel or to connect the source of cooling fluid to said coils in series.

6. In an air conditioning system, in combination, a first coil, refrigerating means including a water cooled condenser to supply refrigerated water to said first coil, a second coil, a supply of cooling water, means responsive to the temperature of the refrigerated water to operate said refrigeration system and to connect said sup-, ply of cooling water to the condenser thereof, and thermostatically controlled means responsive to air temperature to connect said supply of cooling water to said second coil and said condenser in the order named.

7. In an air conditioning system, in combination, a dehumidifying coil, a cooling coil, means to pass air to be conditioned over said coils, a refrigerating system including a water cooled condenser to maintain a supply of refrigerated water for 'said dehumidifying coil, 9, supply of cooling water, means responsive to the refrigerated water temperature to operate said refrigerating system and to connect the supply of cooling water to the condenser thereof, a moisture responsive control in control ofthe flow of refrigerated water to said dehumidifying coil, and thermostatically controlled means responsive to the temperature of the conditioned air operative to connect the supply of cooling water to the cooling coil and said condenser in series.

8. In an air conditioning system, in combination, means to withdraw air from a space and from the outside atmosphere and to deliver said mixture to the space, a refrigerated water coil located in the path of said mixture, a first cooling coil also located in the path of said mixture, a second cooling coil located 'in the path of only the fresh air, means to provide a supply of refrigerated water for said refrigerated water coil and including a water cooled device, and means to direct cooling water through said first cooling coil, second cooling coil, and said device, in series, and in the order named.

9. In combination, in an air conditioning system, a refrigerated coil, a second coil, means to Pass air to be conditioned over said coils, means to supply refrigerated water to said refrigerated coil and including a water cooled device, a supply of cooling water, a supply of heating fluid. valve means in control of the flow of coolingxwater and heating fluid, and control. means selectively operable to-connect the supply of cooling water to said second coil and water cooled device in series or to connect the supply of heating fluid to-said second coil only.

10. In an air conditioning system for a space, a refrigerated coil, a cooling and heating coil, means to supply refrigerated water to said refrigerated coil and including a water cooled device, a supply of cooling water, means responsive to demands for refrigerated water to operate'said means and to direct cooling water to said device, a supply of heating fluid, and means including space temperature responsive means to direct the supply of cooling water through said cooling and heating coil and water cooled device in series upon an increase in space temperature or to direct the supply of heating fluid through said cooling and heating coil only, upon a fall in space temperature.

11; In an air conditioning system for a space,

cluding a water cooled device, a Supply of cooling water, means in control of said means and operable to connect the supply of cooling water to said device, and means including means responsive to the space temperature operable selectively to supply said cooling water to said two combined cooling and heating coils and the Water cooled device in series, or todirect a, supply of heating fluid only to said two combined cooling and heating coils.

12. An air conditioning system, comprising, in combination, means to supply withdrawnair and fresh air to a space, a dehumidifying coil and a cooling coil located in the path of the withdrawn air and fresh air, a second cooling coil located in the path of the fresh air only, a refrigeration system including a water cooled condenser for supplying refrigerated water to said dehumidifying coil, a supply of cooling water, and means responsive to the temperature of the space to control the flow of cooling water through said denser in series.

13. An air condition system of the class described, comprising, in combination, means to supply withdrawn ai'rand fresh air to a space to be conditioned, a dehumidifying coil and a first cooling coil located in the path of travel of both the withdrawn air and fresh air, a second cooling coil located .in the path of travel of only the fresh air, mechanical refrigeration means including a water cooled condenser. to provide refrigerated water for the dehumidifying coil, a moisture responsive control in control of the flow of refrigerated water tothe dehumidifying coil, a supply of cooling water, means to, connect the supply of cooling water tosaid condenser when needed, a supply of he ting fluid, and means including space tempe ature responsive means operable selectively to direct the supply of cooling water through said cooling coils in series and then through said condenser or to direct the supfirst cooling coil, second cooling coil, and conply of heating fluid only through said cooling coils.

14. In an air conditioning system, means to supply air to a space to be controlled, first and second combined heating and cooling coils arranged to change the temperature of said air,

valve means operable to supply cooling fluid'to said coils in series or to supply heating fluid to said coils in parallel, and means responsive to the space temperature and the outdoor temperature in control of said valve means.

15. In an air conditioning system, means to supply airto a space to be controlled, first and second combined heating and cooling coils arranged to change the temperature of said air, valve means to permit or prevent the supplying of heating or cooling fluid to said coils, means responsive to outdoor temperature in control of said valve means, additional valve means to (iirect the flow of the heating and cooling fluid to said coils but subjectto the dominatingaction of said first valve means, and means responsive to space temperature in control of at least a portion of said additional valve means.

16. In an air conditioning system, means for supplying withdrawn air and. fresh air to a space, a dehumidifying coil and a first combined heating and cooling coil located in the path of travel of the withdrawn air and fresh air, a second comhumidifying coil, a moisture responsive control in control of the flow of chilled water to said dehumidifying coil, valve means to permit the supplying of heating fluid to said combined heating and cooling coils or to permit the supplying of cooling fluid to said coils and .condenser, a condenser water valve to control an independent flow of cooling Water to said condenser, means including a thermostat responsive to the temperature of said chilled water in control of the refrigeration" system and said condenser watervalve, and a master control in control of said valve means, said condenser valve, and refrigeration system selectively to operate said valve means to permit a cooling operation and place said chilled water thermostat in control of the condenser water valve and refrigerating system or to operate said valve means to permit aheatwith a supply of heating fluid or to place at least a portion thereof in communication with a supply of cooling fluid, two-position master control means in control of said master valve means, additional valve means to control the flow of said fluids to said coil means,.and means responsive to the temperature of said space and outdoor temperature in-control of said additional valve means.

18. An air conditioning system of the class described, comprising, in combination, means for supplying air to a space, coil means located in the path of said air, masterwalve means selectively operable to connect a source ofheating fluid or a source of cooling fluid to said coil means, a two-position master control in control of said master valve means, additional valve means in control of the flow of heating and cooling fluid to said cell means, means responsive tothrough all of said coil means inseries or to direct the heating fluid through only a portion of said coil means, and means responsive to outdoor temperature to direct heating fluid through another portion of said coil means.

19. In an air conditioning system, means for directing withdrawn air and fresh air to a space to be conditioned, a first coil in the path of both the withdrawn air and fresh air, a second coil in the path of said fresh air only, master valve means selectively operable to connect said coils' to a supply of heating fluid or to a supply of cooling fluid, a two-position master control in control of said master valve means, additional valve means for supplementing the control action of said master valve means, means responsive to the conditions in said space controlling said additional valve means to direct the cooling fluid through said first and second coils in series in the order named or to direct heating fluid through said first coil only, and means responsive to outdoor conditions controlling said additional valve means to direct heating fluid through said second coil.

20. In a combined heating and cooling system,

in combination, means to supply air to a space the temperature of which it is desired to control, coil means'located in the path of said air, a source of heating fluid, a source of cooling fluid,

valve means operable to connect a portion of said.

tem for a space, in combination, means to supply fresh air and air withdrawn from said space to the space, a coil in the path ofthe fresh air, a

second coil in the path of air other than said fresh air, a source of heating fluid, a source of cooling fluid, valve means to selectively direct either the heating fluid or the cooling fluid to said second coil, means responsive to the temperature of the space in control of said valve means, other valve means controlling the flow of one of said fluids to said first coil, and means responsive to outdoor temperature in control of said other valve means. I

22. In a combined-heating and cooling system for a space to be controlled, in combination, means to supply a mixture of fresh air and re turn air to said space, a first coil in the path of said mixture of fresh and return air, a second coil in the path of th fresh air only, a source of heating fluid, a source of cooling fluid, master valve means to selectively permit the supplying of said heating fluid or cooling fluid to said coils,

. means responsive to outdoor temperature incontrol of said master valve means, supplementary valve means additionally controlling th flow of said fluids to said coils, means responsive to the space temperature controlling said supplementary valve means to permit cooling fluid to flow to both of said coils upon rise in space temperature and to permit heating fluid to flow to said first coil only upon fall in thespace temperature, and means responsive to the outdoor temperature additionally controlling said supplementary valve means to permit the flow of heatingfluid to said 23. A combined heating and'cooling system for a space to'becontrolled, comprising, in combination, means to pass fresh air and other air to said space, a first coil in the path of the fresh air and a second coil in the path of the other air, valve means to control the flow of a heating fluid to said coils in parallel and the flow of a cooling fluid through said second coil and then through said first coil in series, and means in control of said valve means including space temperature responsive means and. outdoor temperature responsive means. v

24. An air conditioning system of the class de,- scribed, comprising, in combination, means to pass a mixture of withdrawn air and fresh air to a space, a first coil located in the path of said air mixture, a second coil located in the path of the fresh air only, a source of heating fluid, a source of cooling fluid, pipes connecting said sources of fluid and coils, valve means in control of said connections, and means in control of said valve means selectively to connect the source of heating fluid to both saidcoils in parallel or to connect the source of cooling fluid to said coils in series so that the cooling fluid first passes through said first coil and then through the 4 device or for passing said cooling fluid around said cooling means to said fluid cooled device, and means responsive to the condition of the air for controlling said selective means.

26. In an air conditioning system, in combination, dehumidifying means for the air including a refrigeration system having a fluid cooled device, cooling means for cooling the air, selective means for selectively passing cooling fluid through said cooling means to said fluid'cooled device, or for passing said cooling fluid around said cooling means to said fluid cooled device, means influenced by the temperature of the con-' ditioned air for controlling said selective means, and means influenced by the humidity of the conditioned air for controlling said dehumidifying second coil if the outdoor temperature becomes too low.

means.

,LEO B. MILLER.

HENRY F. DEVER. 

